The present invention relates to an NTSC/PAL subcarrier based H-lock with color framing and detection.
Personal computer graphics programs and the requirements of broadcast video frequently present problems in order to provide true compatibility. One aspect of the compatibility is to provide color frame detection and digital lock to a horizontal sync pulse from an NTSC or PAL video signal.
The NTSC (National Television System Committee) standard is a standard which was named after an all-industry engineering group which developed U.S. color television specifications. The NTSC standard now describes the American system of color telecasting.
The PAL (Phase Alternation Line) standard pertains to a color television system in which the V component of subcarrier derived from a color burst is inverted in phase from one horizontal line to the next in order to minimize hue errors that may occur in color transmission.
The prior art has not been able to provide a single circuit which provides subcarrier based H-lock for both the NTSC and PAL standards. It would therefore be desirable to provide subcarrier based H-lock apparatus with the capability of color framing and detection whether with an NTSC or PAL video signal.